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i L Getty Task 2 Page 31 6.0 CONCLDSIONS AND RECOMMENDATIONS March 1, 1983 Daring the first five years of mining, the estimated mazimum inflow to the mine is approzimately 200 gym. This value includes lateral inflow as well as leakage through the roof from the Twentymile Sandstone. In addition to this amount, inflows through the floor may be as high as 300 gym for short time periods. This amount is based on the assumption that the mine will penetrate intensive fracture zones that allow water to flow upward from the underlying Trout Creek Sandstone. In reality, the inflows through the mine floor will probably be smaller than predicted is this study. Ia any event, some upward flow through the mine floor should be ezpected is the Tiekea Lease area. This flow may have an effect on the stability of the floor end will probably cause some operational problems. Assuming that aquifer parameters for the Trout Creek Sandstone are not significantly different than those assumed for the calculations the mazimnm inflow ezpected to the mine during the first five years of mining is approximately 500 gym. The mnzimum inflow, due to lateral seepage at the face and vertical seepage through the roof, during the entire life of the mine is ezpected to be approzimately 900 gym. As during the first five years of the mine, some inflow through the floor of the mice should be ezpected. Based oa interpretation of the piezometric surface of the overbnrdea aquifer, it is I unlikely that large amounts of upward vertical flow occur in areas other than the Tiekea Lease area. Because of this, it is not ezpected that large floor L inflows will occur after the first five years of mining. It is anticipated that the mining operation will not significantly effect the groundwater quantity or quality in either the Twentymile aquifer or the Trout Creek aquifer. It is likely that the amount of discharge is Fish Creek will decline slightly due to the dewateriag of the overbnrdea aquifer, the L amount of reduction ezpected is insignificant when compared to the aversge sannal discharge of this stream. In fact the redaction is flow is only L approzimately aae percent of the amount of flow gain currently realized by Fish Creek as it traverses Tweatymile Park. The amount of water actually ~ discharged to the surface water streams is the area will probably increase i daring the mining period since water removed from the mine will eventually be discharged to these streams. u u J